Merge pull request #3 from renato-iar/feature/add-retries-and-fallbacks

Feature/add retries and fallbacks

Author: renato-iar

README.md

@@ -92,6 +92,32 @@ struct Book {
 
 This will cause `synopsis` to not be safely decoded in the initializer.
 
+The `@FallbackDecoding` macro can be used to grant fallback semantics to properties.
+`@FallbackDecoding` must be used with `@SafeDecoding`, and means decoding will never fail properties it is applied to (even if the type is not otherwise "safe-decodable"):
+
+```swift
+@SafeDecoding
+struct Book {
+    @FallbackDecoding(false)
+    var isFavourite: Bool
+}
+```
+
+The `RetryDecoding` macro can in turn be used to provide alternative decoding of a property; an alternative decoding type and a "mapper" between types must be provided.
+An example could be a backend that sometimes returns integers as strings, or booleans as integers:
+
+```swift
+@SafeDecoding
+struct Book {
+    @RetryDecoding(String.self, map: { $0.lowercased() == "true" })
+    @RetryDecoding(Int.self, map: { $0 != 0 })
+    var isFavourite: Bool
+}
+```
+
+Retries will be performed in the same order as they are declared in the property.
+If `@FallbackDecoding` is used alongside retries, all retries will be attempted before the value specified for fallback is used.
+
 ## Installation
 
 ### Swift Package Manager
@@ -102,3 +128,42 @@ You can use the Swift Package Manager to install your package by adding it as a
 dependencies: [
     .package(url: "https://github.com/renato-iar/SafeDecoding.git", from: "1.0.0")
 ]
+```
+
+Finally, `@SafeDecoding` can report errors that occur (and are recovered from) during the decoding process.
+This is done by passing the `reporter:` parameter to the macro:
+
+```swift
+@SafeDecoding(reporter: ...)
+struct Book {
+    ....
+}
+```
+
+The reporter must conform the `SafeDecodingReporter` protocol.
+Upon recovery of decoding errors, the reporter will be called with information about said error.
+Remember that a reporter is local to its type, i.e. although the same type may be used everywhere **each @SafeDecoding usage must be given its reporter expression**.
+
+# Versions
+
+## Version 1.3.0
+
+- Add `@RetryDecoding`, allowing individual properties to have associated retries
+- Add `@FallbackDecoding`, allowing individual properties to provide a last-resort value 
+
+## Version 1.2.1
+
+- Bug: uses `decodeIfPresent` for optionals when using error reporting
+
+## Version 1.2.0
+
+- Accounts for access modifiers
+
+## Version 1.1.0
+
+- Add error reporting to `@SafeDecoding` macro
+- Remove sample client product
+
+## Version 1.0.0
+
+- Add `@SafeDecoding` and `@IgnoreSafeDecoding` macros

Sources/SafeDecoding/ExampleClient/main.swift

@@ -48,10 +48,11 @@ struct SubModel {
     let strings: Array<String>
 }
 
+// Expand macro to see code generated for the base usage of @SafeDecoding
+
 @SafeDecoding
-struct NonReportedModel {
+struct ModelStandardExample {
     let integer: Int
-    @IgnoreSafeDecoding
     let integerArray: [Int]
     let genericArray: Array<String>
     let string: String
@@ -64,15 +65,26 @@ struct NonReportedModel {
     let constantInferred = 0
 }
 
+// Expand macro to see code generated for extended usage of @SafeDecoding
+// using the reporter, as well as @RetryDecoding, @FallbackDecoding and @IgnoreSafeDecoding
+// macros as decorators
+
 @SafeDecoding(reporter: SafeDecodingErrorReporter.shared)
-struct ReportedModel {
+struct ModelFullExample {
+    @RetryDecoding(String.self, map: { Int($0, radix: 10) })
+    @RetryDecoding(Double.self, map: { Int($0) })
     let integer: Int
     @IgnoreSafeDecoding
     let integerArray: [Int]
     let genericArray: Array<String>
+    @FallbackDecoding(UUID().uuidString)
     let string: String
     let dictionary: [String: Int]
+    @FallbackDecoding(0)
+    @RetryDecoding(String.self, map: { Int($0, radix: 10) })
+    @RetryDecoding(Double.self, map: { Int($0) })
     let optionalInteger: Int?
+    @FallbackDecoding(SubModel(strings: []))
     let subModel: SubModel?
     var numberOfIntegersInArray: Int { integerArray.count }
     let set: Set<Int>
@@ -83,7 +95,7 @@ struct ReportedModel {
 let input = """
 {
     "integerArray": [1, 2, 3],
-    "integer": 0,
+    "integer": "101",
     "string": "hello",
     "dictionary": {
         "a": 1,
@@ -99,7 +111,7 @@ let input = """
 do {
     if let data = input.data(using: .utf8) {
         let model = try JSONDecoder().decode(
-            ReportedModel.self,
+            ModelFullExample.self,
             from: data
         )
 

Sources/SafeDecoding/Macros/Macros/FallbackDecodingMacro.swift

@@ -0,0 +1,12 @@
+import SwiftSyntax
+import SwiftSyntaxMacros
+
+public enum FallbackDecodingMacro: PeerMacro {
+    public static func expansion(
+        of node: AttributeSyntax,
+        providingPeersOf declaration: some DeclSyntaxProtocol,
+        in context: some MacroExpansionContext
+    ) throws -> [DeclSyntax] {
+        []
+    }
+}

Sources/SafeDecoding/Macros/Macros/RetryDecodingMacro.swift

@@ -0,0 +1,13 @@
+import SwiftSyntax
+import SwiftSyntaxBuilder
+import SwiftSyntaxMacros
+
+public enum RetryDecodingMacro: PeerMacro {
+    public static func expansion(
+        of node: AttributeSyntax,
+        providingPeersOf declaration: some DeclSyntaxProtocol,
+        in context: some MacroExpansionContext
+    ) throws -> [DeclSyntax] {
+        []
+    }
+}